Improvement in utilizing tin-scrap and manufacture of stannates



' HnIrEn s -mtssmtsm sons ITOLLIDAY AND JOHN LAMBERT, or BROOKLYN,ASSIGNORS 'ro WILLIAM SLAOK,;O I STAPLETON, NEW YORK.

IMPROVEMENT IN UTILIZINGTIN-SC-RAP AND MANUFACTURE OF-STANNATES.

1878; application filed December 24, 1877.

7 following is a specification The tin scraps or metallic tin aretreated in a solution of caustic soda, nitrite of soda, arsenite ofsoda, and nitrate of soda.

The best proportions are as follows: two hundredpartscommcrcialcausticsoda, seventy parts nitrite of soda, one hundred and thirty .part'sarsenite of soda, and fifty partsnitrateof soda.

The above chemicals are dissolved in suflic ent water to have whendissolved a solution gaging from 15 to 18 Banm.

It Is preferable to have over the tank used i'or this operation a cover,connecting with a high chimney, to take away the gases evolved in theoperat1on, such .as' arseniureted hydrogen and ammonia. This bath, whichwe will call areacti on-bath, is kept at about 180 Fahrenheit, and

tin scraps or metallic tin introduced 1nto the same.

When the bath is new a charge of tin scraps or metallic tin requiresabout two hours to finish. Every fresh charge of tin scraps rcqun'es.more time until the bath is worked out.

' \Vhen' taken out of the reaction-bath the tin scraps are washed withwater once or twice.

The' water from the first washing is used to replace the evaporationfrom the-reaction-bath.

' When worked out the reaction-bath contains in solution stannate ofsoda and caustic soda, whlch can be saturated by adding some stannicacid obtained by precipitation of the washlHg-IIqHOI'S with sulphuricacid, and thus the solution becomes stannate of soda. When the solutionof stannate of soda has thus been saturated it is evaporated to dry thesalt.

Instead of evaporating the stannate-of-soda liquors, the stannicacid canbe precipitated directly from them by adding some sulphuric or muriatlcacid. The stannic acid thus obtained can be transformed into block-tinby the ordinary processes.

. Tin can also be removed from the tin scraps by using only abathcontaining, with caustic soda, either arsenite of soda or'uitrite ofsoda.

The proportions, with caustic soda and arson .of soda ammonia isevolved.

ite'of soda alone, having given the best results are: caustic soda,ninety parts; arsenite. of soda, one hundred and. thirty parts. With andarsenite of soda, arseninreted hydrogen.

is evolved, and with caustic soda and nitrite This latter could becondensed in a proper apparatus for the production of ammonia or saltsof ammonia.

W'hen arsenic'is present, and it is desired to remove the same entirely,the operation is continued until the same is driven off as arseniuretedhydrogen.

The iron scraps freed from tin can be worked into iron. a

We wish it to be understood that the proportions of materials may beslightly varied as long as the same result is attained.

Heretofore, when tin has been removed from scrap-iron by caustic sodaand nitrate of soda, peroxide of manganese or similar material, such aslitharge, has been present to furnish, by its decomposition, the oxygenrequired in oxidizing the tin. v

.By our process the man ganesc or similar material is dispensed with,and the-stannates are pure and free from foreign matter, because thenitrite, nitrato, or arsenite oxidizes the tin directly, and thenitrogen or arsenic set free reacts on the water, decomposing the sameby combining with the hydrogen. The oxygen l'berated promotes theoxidation of the tin, a d the staunate'is produced free from foreignmatter. Y

\Ve claim as our invention The reaction-bath for the manufacture ofstannic salts, composed of a solution of canstic soda or potash inconnection,alone, with one or more of those agents which, acting withthe tin and the oxygen of the water,

produce stannic salts, such as alkaline arsenites, nitrates, ornitritcs,substantially as set forth.

Signed by us this 18th day of December, A. I). 1877.

J. LAMBERT.

Witnesses:

GEO; T. PJNGKKEY, CHAS. II. 'SMiTB.

'OFFIGE.

JOHN HoLLniAY.

